1. Field of the Invention
This invention relates to a cylinder block for an internal combustion engine, and more particularly to a cylinder block for an internal combustion engine having an increased transverse rigidity.
2. Description of the Prior Art
As is disclosed in Japanese Unexamined Utility Model Publication No. 55(1980)-88047, there has been known a structure of a cylinder block for an internal combustion engine in which the side walls of the cylinder block are formed of a plurality of bight portions to suppress membrane vibration, thereby reducing vibration and noise of the engine.
However, the structure of the cylinder block disclosed in the Japanese Utility Model Publication is disadvantageous in that since nodes are defined at the junctions between adjacent bight portions which are located in the same positions in both the side walls, the rigidity of the overall cylinder block structure against lateral bending is weakened to create a primary vibrational-noise producing factor, though membrane vibration of the side walls can be effectively suppressed by forming the side walls of a plurality of bight portions. Especially, in a diesel engine, suppression of the vibrational noise is highly important.